The human androgen insensitivity syndrome (AIS) results from a variety of mutations in the androgen receptor (AR) gene that cause differing degrees of incomplete male sexual development. The objectives of this proposal will make use of natural and site directed AR gene mutation to investigate structure-function relationships of human AR and identify receptor associated factors that mediate androgen action. We will investigate the structural determinants of androgen binding kinetics and AR stability by examining AIS mutations that alter the NH2-/carboxyl- terminal interaction during androgen dependent AR dimerization. Mutant and wildtype AR will be analyzed in a mammalian cell two-hybrid protein- protein interaction assay to map sites of interaction between the NH2- carboxyl terminal regions. Experiments are designed to investigate the recently proposed antiparallel structure of the ligand activated AR dimer. Structural determinants of AR ligand binding specificity will be performed within the context of the AR ligand binding domain three- dimensional structure as predicted from recent crystal structure determination of other nuclear receptors and responsiveness to a variety of synthetic androgens will be tested. Identifications of ligand binding domain amino acid residues required for AR protein/protein interactions will focus on a recently identified protein fraction that interacts with the unoccupied AR ligand binding domain and appears to require both androgen binding and interaction with the AR NH2-terminal region for its displacement. Through the analysis of mutants, we will identify NH2- terminal amino acid residues critical for AR transactivation and protein- protein interactions. Factors that regulate AR mRNA stability and expression will be investigated in AIS subjects that lack a mutation in the gene coding region. We will pursue preliminary evidence that the phenotype of androgen resistance associated with adult spinal/bulbar muscular atrophy results from transciptional interference rather than a defective AR.